1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to color reproduction, and more particularly, to image-adaptive color reproduction, which can reproduce optimal image-adaptive colors.
2. Description of the Related Art
Digital imaging apparatuses for reproducing colors, such as monitors, scanners, printers are of high quality, have been provided with diversified functions in order to satisfy various user demands, and use different color spaces or color models according to respective application fields. Color space models can be divided into device-dependent models and device-independent models. The former includes the Red, Green, Blue (RGB) model, which is a kind of additive color space model, and a Cyan, Magenta, Yellow, Black (CMYK) color space model, which is a kind of subtractive color space model. The latter includes the Commission Internationale d'Eclairage (CIE) Lab model, CIE XYZ model, CIE LUV model and so forth. The CMYK color space model is mainly used in the printing field, and the RGB color space model is mainly used in fields employing a computer monitor.
Information regarding an image that is viewed through imaging equipment cannot completely represent real colors. Thus, imaging equipment represents colors by removing visually unperceivable portions, and providing more information regarding visually perceivable portions or portions exhibiting perceivable color differences. Particularly, since the human visual system is most sensitive to luminance changes, the picture quality of a printer is generally affected by changing luminance and adjusting luminance contrast.
With respect to luminance reproduction, several related art methods have been disclosed, including a method in which separate luminance regions are established and the established luminance regions are compressed in different directions from region to region (U.S. Pat. No. 5,883,632), a luminance reproduction method using a low-pass filter (U.S. Pat. No. 6,646,762), and a method in which contrast is selectively extended and simultaneously hues are preserved according to input video signal levels (Korean Patent Application No. 2002-0050071). However, these related art methods have a problem in that they use a single algorithm for the luminance reproduction, which makes it impossible to reproduce image-adaptive colors.
Also, several luminance-saturation remapping methods have been disclosed, including a method in which a gamut is mapped by adjusting a Lookup Table (LUT) in an image processing process (U.S. Pat. No. 6,724,935), and a method in which a gamut of each device is comparison-mapped in a device-independent space (U.S. Pat. No. 6,719,392). However, theses related art methods have a problem in that an image is reproduced on a pixel-by-pixel basis, and thus color reproduction is carried out without considering the relationship between each pixel and its surrounding pixels.
That is, the related art methods are problematic in that image reproduction is accompanied by a great difference in image quality because a single algorithm is applied to images having different characteristics, and color reproduction is performed without regard for the harmonization of surrounding colors due to color processing on a pixel-by-pixel basis.